[3.19.y-ckt stable] Patch "xen/gntdev: Grant maps should not be subject to NUMA balancing" has been added to staging queue

[Kamal Mostafa]

This is a note to let you know that I have just added a patch titled

    xen/gntdev: Grant maps should not be subject to NUMA balancing

to the linux-3.19.y-queue branch of the 3.19.y-ckt extended stable tree 
which can be found at:

    http://kernel.ubuntu.com/git/ubuntu/linux.git/log/?h=linux-3.19.y-queue

This patch is scheduled to be released in version 3.19.8-ckt12.

If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 3.19.y-ckt tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Kamal

------

>From f20dd2059f249cf05f14dbedd19604bf811bdb8f Mon Sep 17 00:00:00 2001
From: Boris Ostrovsky <boris.ostrovsky at oracle.com>
Date: Tue, 10 Nov 2015 15:10:33 -0500
Subject: xen/gntdev: Grant maps should not be subject to NUMA balancing

commit 9c17d96500f78d7ecdb71ca6942830158bc75a2b upstream.

Doing so will cause the grant to be unmapped and then, during
fault handling, the fault to be mistakenly treated as NUMA hint
fault.

In addition, even if those maps could partcipate in NUMA
balancing, it wouldn't provide any benefit since we are unable
to determine physical page's node (even if/when VNUMA is
implemented).

Marking grant maps' VMAs as VM_IO will exclude them from being
part of NUMA balancing.

Signed-off-by: Boris Ostrovsky <boris.ostrovsky at oracle.com>
Signed-off-by: David Vrabel <david.vrabel at citrix.com>
Signed-off-by: Kamal Mostafa <kamal at canonical.com>
---
 drivers/xen/gntdev.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/xen/gntdev.c b/drivers/xen/gntdev.c
index 91cc446..7ffbb93 100644
--- a/drivers/xen/gntdev.c
+++ b/drivers/xen/gntdev.c
@@ -765,7 +765,7 @@ static int gntdev_mmap(struct file *flip, struct vm_area_struct *vma)

 	vma->vm_ops = &gntdev_vmops;

-	vma->vm_flags |= VM_DONTEXPAND | VM_DONTDUMP;
+	vma->vm_flags |= VM_DONTEXPAND | VM_DONTDUMP | VM_IO;

 	if (use_ptemod)
 		vma->vm_flags |= VM_DONTCOPY;
--
1.9.1